Presowing treatments and temperature regimes were tested to improve germination of Alstroemeria hybrids 3 to 12 months following harvest. In addition, seeds from 20 intraspecific F1 hybrids of five selections were also tested 3 to 7 or 8 to 12 weeks following harvest. Seeds were pretreated by chipping the seedcoat above the embryo, general abrasion of the entire seedcoat, or soaking 12 hours in distilled water, GA, (0.029, 0.29, 2.9 mm), or KNO3 (0.5 and 1.0 m). Pretreatments were evaluated under three environmental regimes: 8 weeks at a constant 18-25C (warm), 4 weeks at 18-25C followed by 4 weeks at 7C (warm-cold), or 4 weeks at 7C followed by 4 weeks at 18-25C (cold-warm). There was an interaction between pretreatment and environmental regime for percent germination. Germination percentages for the water soak and GA, at 0.29 or 2.9 mm were significantly higher than for the other pretreatments, but were not significantly different from one another. The warm-cold environment yielded higher germination percentages than the other environments. The time to germination was longest for the cold-warm regime. This response depended on the genotype and the age of the seed. Chemical name used: gibberellic acid (GA3).
Joseph J. King and Mark P. Bridgen
I.E. Yates and Darrell Sparks
publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must hereby be marked advertisement solely to indicate this fact.
Leslie K. Lake, Warren E. Shafer, Sheryl K. Reilly, and Russell S. Jones
Plant growth regulators (PGRs) are often used in crop production for specific niche market needs. PGRs are frequently viewed as secondary business opportunities by the private sector, especially when compared to herbicide, insecticide, and/or fungicide markets. Nonetheless, PGRs are regulated by the U.S. Environmental Protection Agency (USEPA), and the additional cost of regulatory compliance as part of commercial development is significant. Of the two broad classes of pesticides regulated by the USEPA, conventional chemicals and biological pesticides (or biopesticides), many PGRs belong to the biopesticide class, specifically the biochemical category. Because of USEPA's responsibility to assure that any pesticide used in commerce will not result in unreasonable adverse effects to humans or the environment, specific data requirements have been established for product registration. Registrants must address each requirement, either by submitting relevant data or a request to waive the requirement, prior to receiving a federal registration. For biochemical PGRs, the acceptability of data or waiver requests, as well as any proposed label uses, are reviewed by the Biopesticides and Pollution Prevention Division (BPPD). The BPPD was formed in 1994 to facilitate the development of biopesticide products. Given the time and expense associated with PGR product development and commercialization, registrants should work closely with the USEPA and other stakeholders to help ensure successful product development.
Calin O. Marian, Atilla Eris, Stephen L. Krebs, and Rajeev Arora
The influence of photoperiod and temperature on the seasonal (fall to winter) cold acclimation and accumulation of a 25 kDa dehydrin in Rhododendron `Chionoides' was studied by exposing two groups of plants each in the greenhouse or outdoors to either a natural photoperiod (or short days) or an extended photoperiod (or long days) regime. Results suggest that the shortening daylength alone is sufficient to trigger both the first stage of cold acclimation and concomitant 25 kDa dehydrin induction. Exposure of the plants to natural photoperiod and temperatures induced the greatest cold hardiness and 25 kDa accumulation, while exposure to extended photoperiods (long days) and warmer temperatures (in the greenhouse) failed to induce any significant freezing tolerance in leaves. Whereas short days trigger the cold acclimation process initially, low inductive temperatures can eventually replace the photoperiod stimulus. Seasonal accumulation of 25 kDa dehydrin, on the other hand, appears to be predominantly effected by short photoperiods. Data indicated that the leaf water content of outdoor plants maintained under natural photoperiod was lower than that of plants grown under extended photoperiod. This was also true for the greenhouse plants at the first (September) and the last (January) sampling. It is hypothesized that early 25 kDa dehydrin accumulation may be due to short-day-induced cellular dehydration. Accumulation of two other dehydrins of 26 kDa and 32 kDa molecular masses does not appear to be associated with short day (SD)-induced first stage of cold acclimation. Results show that their accumulation may be regulated by low, subfreezing temperatures and may be associated with the second and/or third stage of cold acclimation of `Chionoides' rhododendron leaves.
Coleman L. Etheredge and Tina M. Waliczek
general public see the value of such a program ( Bradley, 2014 ; EPA, 2019). The trend of environmental self-regulation, willingly imposing more stringent environmental policies than those required by the government, is progressing toward a time where
Tanya J. Hall, Jennifer H. Dennis, Roberto G. Lopez, and Maria I. Marshall
environmental regulation, customer-perceived value of the practice in question, grower attitudes toward the practice, and grower demographic characteristics. Environmental regulations. Environmental regulations are environmental laws imposed by state and
Holly A. Little, Rebecca Grumet, and James F. Hancock
environmental conditions, reduce chemical inputs, or tailor plants for nutritional or industrial needs. Unlike genes used in the first wave of transgenic crops, these types of genes are intended to modify gene regulation or metabolic or signaling pathways of the
Rui Wang, Yuqing Gui, Tiejun Zhao, Masahisa Ishii, Masatake Eguchi, Hui Xu, Tianlai Li, and Yasunaga Iwasaki
to sucrose in leaves and overall productivity of plants ( Gotoh et al., 2018 ; Heuvelink and Marcelis, 1996 ). In natural environments or field production conditions, the plant must integrate complex environmental factors to adjust flower initiation
Jennifer H. Dennis, Roberto G. Lopez, Bridget K. Behe, Charles R. Hall, Chengyan Yue, and Benjamin L. Campbell
container types used, and 10 open-ended questions based on demographic and industry priorities. It asked respondents about the importance of sustainability, views of state environmental regulations, sustainable practices in place, sustainable practices they